The code originally used in The Haskell School of Expression relied on a
graphics library called SOEGraphics, which in turn depended on a more
primitive, but not-very-portable, graphics library called HGL.

We now recommend down-loading the source code for SOE
below, which imports a new graphics library called simply SOE. The
SOE library uses a highly-portable graphics package based on OpenGL. Alternatively, there is a
version based on Gtk, although it is not quite as portable as the former.
In both cases we recommend using GHC (and GHCi) as the Haskell compiler (and
interpreter). Both methods for installing SOE are described below.

Acknowledgements: Thanks to Paul Liu for
writing the GLFW package, and to Duncan Coutts for writing the Gtk2Hs library
for SOE (some of the code from that is in fact used in GLFW).

We recommend using the Glasgow Haskell Compiler (GHC)
version 6.8 or later. The easiest way to install GHC is by downloading the
latest Haskell Platform, which
includes an installation package called Cabal. If you install GHC
in some other way, you may have to install Cabal on your own -- see
http://www.haskell.org/haskellwiki/Cabal-Install.

OpenGL

This is the recommended way to use SOE,
relying on the OpenGL and GLFW packages for better cross-platform support
than was previously available.

Step 1: Install the Haskell packages that SOE depends
on. To do this, open a command prompt and enter:

cabal install GLFW

This will download, configure, and install the GLFW
Haskell package into your system. It may also automatically download and
install the OpenGL Haskell package for you if your system does not already have
it.

The SOE source code requires no installation once GLFW is installed.
Simply place the SOE code where you want it, load any module into GHCi, and hope
for the best!

Note for OS X users: running graphics applications from GHCi is no longer supported. Instead, one has to compile a graphics program using GHC in order to run it (see example/GMIExamples.lhs for an example). Running non-graphics operations, such as MIDI playing, from GHCi may be fine and not affected.

Gtk2Hs

Instead of using
OpenGL / GLFW, an alternative way to run SOE source code is to use the module
Graphics.SOE.Gtk instead of the SOE.hs included in the source above. To do
this, follow the installation instructions for Gtk2Hs at
http://www.haskell.org/gtk2hs, then import the module Graphics.SOE.Gtk
instead of SOE.hs in your code.

Although both platforms have their advantages from a
graphics point of view, keep in mind that: